There are some circumstances where an unauthorized user will open up a web browser with the intention of hitting the Splash page to authenticate, but the web browser times out or fails to load the page. This will commonly occur when the user was attempting to access a web site via HTTPS.
When the AP or security appliance sees an HTTP GET request from a non-authenticated user, it will redirect that request to its configured Splash page. If the user's initial request is using HTTPS, however, their request is encrypted and therefore cannot be redirected. As such, the request will time out.
To troubleshoot this issue, the user should clear their browser cache and try to access any website using HTTP. If the issue persists, ensure that the client has a valid IP configuration, and troubleshoot for other possible network issues.
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
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